西北太平洋岛弧系列成因的探讨

THE GENESIS OF THE NORTHWEST PACIFIC ISLAND ARC SYSTEM

西北太平洋岛弧系列中的各岛弧(除马里亚纳岛弧为洋壳型弧外)均由陆壳型弧和洋壳型弧组成,并且左端与大陆相连,右端被后形成的岛弧所截。整个岛弧系列,从中生代末期开始发育至今,由北向南依次发展,规律明显。

The paper mainly discusses the association relation and evolution sequence ofthe Northwest Pacific island arcs and puts forward the mode of motion of the Pa-cific plate. Each island arc in the Northwest Pacific island arc system is composed ofcontinental crust arc and oceanic crust arc (except for the Mariana island arc). Thecontinental crust arc is a part of continental crust separated from continental mar-gins oceanwards when a back-arc basin was formed. It is located on the concave sideof an island arc. Each continental crust arc has a complete shape. Its left end(thefront is the convex direction of the island arc) joins the continent, while its rightend is cut by a late-formed adjacent island arc. The oceanic crust arc was formedin the process of subduction of oceanic crust. It is melange resulting from mixingof continental and oceanic crustal materials. It, parallel to a deep trench, is locatedon the convex side of an island arc. The Northwest Pacific island arc system hasevolved from the terminal Mesozoic up to the present. It shows a distinct regular-ity of south-younging.